This invention relates to railroad cars, and more particularly, to an improved brake system therefor, particularly cars employing single axle trucks.
Conventional railroad cars include a car body supported for movement over a pair of rails by one or more wheel trucks. A brake system is normally provided including brake shoes operable to frictionally engage the wheels and slow or stop the car.
Many railroad car brake systems include a cylinder and piston for actuating the brake shoes into frictional engagement with the wheels. The conventional cylinder and piston employed is a cast iron construction which is relatvely heavy and cumbersome. On modern, fuel efficient cars, weight is a major concern. Elimination of excess weight through use of single axle trucks is a clear advantage. Reduction of weight in the brake system, therefore, is a distinct improvement.
Many conventional brake systems are "single acting", i.e., employ only one brake shoe engaging each wheel and require the, relatively heavy cast iron cylinder and piston construction. Attempts have been made to reduce the required brake application force by utilizing "double acting" systems where opposed brake shoes sandwich or clamp the wheels between them. This is particularly true in single axle wheel trucks which have only two wheels. One of the problems here has been that slack develops as the brake shoes wear causing the parts to undergo increased travel during brake application. Slack take-up in double acting systems has been difficult to achieve.
The present invention is directed to a brake system for railroad cars which minimize weight through elimination of the normal cast iron piston and cylinder and yet is efficient and can be utilized with single axle wheel trucks. It is constructed to automatically adjust for wear of the brake shoes and provides for a relatively constant brake application force throughout the life of the brake shoes.